1. Field of the Invention
The present invention relates to an electron beam irradiation apparatus, for example, an irradiation apparatus for electron beam lithography to be used for pattern irradiation of a resist with an electron beam, in original disc fabrication in the case where an optical recording medium, an optical magnetic recording medium, a phase change recording medium, a magnetic recording medium, or the like is formed by using the injection molding, 2P method (Photopolymerization method), or the like. The present invention also relates to an electron beam irradiation method, an original disc, a stamper, and a recording medium.
2. Description of the Related Art
In recent years, a much higher density is demanded for various information recording media such as optical disks, optical magnetic disks, and phase change disks. Fine formation of data recording pits and grooves such as track grooves on the recording media is demanded.
As a result, formation of a finer uneven pattern is demanded in fabrication of the above described original disk as well.
In the fabrication of such an original disc, a resist layer coated and formed on a substrate is subjected to pattern exposure of laser light. By development, a fine pattern is formed on the resist layer. For example, nickel plating is conducted thereon. A stamper having an inversion pattern of the fine pattern, or a master stamper or mother stamper for fabricating stampers is formed.
In such a method, by relative movement between a laser light spot and the substrate caused by rotation of, for example, the substrate along the substrate surface and for example, a unidirectional movement of the substrate along the substrate surface, the top of the resist layer is scanned with the spot in a spiral form or a concentric form. While scanning is thus being conducted, laser light is modulated by a recording signal. Thereby, exposure of a recording pattern is conducted.
In the case where such an exposure method using laser light is used, however, there is a restriction in spot diameter due to an optical limit caused by the laser wavelength and there occurs a problem in forming a sufficiently fine pattern.
On the other hand, in the case where an electron beam is used, a finer pattern can be implemented.
In the case where this electron beam exposure is used, however, work in a vacuum chamber is needed in order to prevent the electron beam from colliding with a gas molecule and being scattered thereby, and consequently the apparatus size becomes large. In addition, the structure is complicated by the above described substrate rotation, movement drive mechanism, signal wiring vacuum seal, and so on. An increase in the apparatus price is thus incurred. Consequently, a cost increase in, for example, the above described original disc, and a cost increase in, in its turn, the recording medium are incurred.
Against this, apparatuses capable of avoiding the use of such a large-scale vacuum chamber have been proposed in, for example, Japanese Patent Application Laid-Open Publication No. 11-288529 and Japanese Patent Application Laid-Open Publication No. 11-328750. In the proposed apparatuses, a diaphragm capable of transmitting an electron beam is provided in an electron optical barrel so as to be able to keep vacuum only inside of an electron beam column housing an electron gun, a condensor electron lens, deflection means, focus adjustment means, and so on therein. The electron beam is adapted to pass through a space in which helium is supplied only in a short beam path between the electron beam column and a disposition portion of a substrate having a resist layer. The disposition portion of the substrate, i.e., a rotation and movement mechanism portion of the substrate is disposed in the atmosphere. The portion held in the high vacuum state is thus reduced. The apparatus is thus reduced in size and made simpler.